how long had your "dud" been in there?
chances are, they are making queen cells from whatever good eggs they could find. they may have known that the queen you had was not great, or as often happens, they didn't like the queen from the package. you probably didn't need to order a queen if they were making cells on the frame you gave them. they would have superseded the old queen with the new.
as for making queen cells from drone larvae, i think they might try. i had a hive that i was reasonably certain was queenless. bad attitude, tons of drone cells, no worker brood. they did make and tear out several queen cells. one or two had larva, but no jelly and they never finished the cells. to my surprise, they have made a queen from brood i gave them, but it took weeks and several frames of brood.
you found the old queen and killed her?